function y = computeEnhancedStrainOperator(e,xi)
f = e.getFace();
J0 = f.jacXAt([0 0]);
j0 = det(J0);
j = det(f.jacXAt(xi));
F0 = [J0(1,1)^2 J0(2,1)*J0(1,2) 2*J0(1,1)*J0(1,2);
    J0(1,2)*J0(2,1) J0(2,2)^2 2*J0(2,1)*J0(2,2);
    J0(1,1)*J0(2,1) J0(1,2)*J0(2,2) (J0(1,1)*J0(2,2)+J0(1,2)*J0(2,1))];
E = [xi(1) 0 0 0;
    0 xi(2) 0 0;
    0 0 xi(1) xi(2)];
y = j0/j*inv(F0)'*E;
end
